搜索结果: 'methocult media formulations for mouse hematopoietic cells serum containing'

During ontogenesis and the entire adult life hematopoietic stem and progenitor cells have the capability to migrate. In comparison to the process of peripheral leukocyte migration in inflammatory responses,the molecular and cellular mechanisms governing the migration of these cells remain poorly understood. A common feature of migrating cells is that they need to become polarized before they migrate. Here we have investigated the issue of cell polarity of hematopoietic stem/progenitor cells in detail. We found that human CD34(+) hematopoietic cells (1) acquire a polarized cell shape upon cultivation,with the formation of a leading edge at the front pole and a uropod at the rear pole; (2) exhibit an amoeboid movement,which is similar to the one described for migrating peripheral leukocytes; and (3) redistribute several lipid raft markers including cholesterol-binding protein prominin-1 (CD133) in specialized plasma membrane domains. Furthermore,polarization of CD34(+) cells is stimulated by early acting cytokines and requires the activity of phosphoinositol-3-kinase as previously reported for peripheral leukocyte polarization. Together,our data reveal a strong correlation between polarization and migration of peripheral leukocytes and hematopoietic stem/progenitor cells and suggest that they are governed by similar mechanisms. View Publication

There are several different technical approaches to the isolation of hematopoietic stem cells (HSCs) with long-term repopulating ability,but these have problems in terms of yield,complexity,or cell viability. Simpler strategies for HSC isolation are needed. We have enriched primitive hematopoietic progenitors from murine bone marrow of mice from different genetic backgrounds by lineage depletion followed by selection of cells with high aldehyde dehydrogenase activity using the Aldefluor reagent (BD Biosciences,Oxford,U.K.). Lin- ALDH(bright) cells comprised 26.8 +/- 1.0% of the total Lin- population of C57BL6 mice,and 23.5 +/- 1.0% of the Lin- population of BALB/c mice expressed certain cell-surface markers typical of primitive hematopoietic progenitors. In vitro hematopoietic progenitor function was substantially higher in the Lin- ALDH(bright) population compared with the Lin- ALDH(low) cells. These cells have higher telomerase activity and the lowest percentage of cells in S phase. These data strongly suggest that progenitor enrichment from Lin- cells on the basis of ALDH is a valid method whose simplicity of application makes it advantageous over conventional separations. View Publication

ETS2 and ERG are transcription factors,encoded on human chromosome 21 (Hsa21),that have been implicated in human cancer. People with Down syndrome (DS),who are trisomic for Hsa21,are predisposed to acute megakaryoblastic leukemia (AMKL). DS-AMKL blasts harbor a mutation in GATA1,which leads to loss of full-length protein but expression of the GATA-1s isoform. To assess the consequences of ETS protein misexpression on megakaryopoiesis,we expressed ETS2,ERG,and the related protein FLI-1 in wild-type and Gata1 mutant murine fetal liver progenitors. These studies revealed that ETS2,ERG,and FLI-1 facilitated the expansion of megakaryocytes from wild-type,Gata1-knockdown,and Gata1s knockin progenitors,but none of the genes could overcome the differentiation block characteristic of the Gata1-knockdown megakaryocytes. Although overexpression of ETS proteins increased the proportion of CD41(+) cells generated from Gata1s-knockin progenitors,their expression led to a significant reduction in the more mature CD42 fraction. Serial replating assays revealed that overexpression of ERG or FLI-1 immortalized Gata1-knockdown and Gata1s knockin,but not wild-type,fetal liver progenitors. Immortalization was accompanied by activation of the JAK/STAT pathway,commonly seen in megakaryocytic malignancies. These findings provide evidence for synergy between alterations in GATA-1 and overexpression of ETS proteins in aberrant megakaryopoiesis. View Publication

Human embryonic stem cells (hESCs),due to their self-renewal capacity and pluripotency,have become a potential source of transplantable $\$-cells for the treatment of diabetes. However,it is imperative that the derived cells fulfill the criteria for clinical treatment. In this study,we replaced common Matrigel with a synthetic peptide-acrylate surface (Synthemax) to expand undifferentiated hESCs and direct their differentiation in a defined and serum-free medium. We confirmed that the cells still expressed pluripotent markers,had the ability to differentiate into three germ layers,and maintained a normal karyotype after 10 passages of subculture. Next,we reported an efficient protocol for deriving nearly 86% definitive endoderm cells from hESCs under serum-free conditions. Moreover,we were able to obtain insulin-producing cells within 21 days following a simple three-step protocol. The results of immunocytochemical and quantitative gene expression analysis showed that the efficiency of induction was not significantly different between the Synthemax surface and the Matrigel-coated surface. Thus,we provided a totally defined condition from hESC culture to insulin-producing cell differentiation,and the derived cells could be a therapeutic resource for diabetic patients in the future. View Publication

Embryonic stem cells are self-renewing pluripotent cells with competency to differentiate into all three-germ lineages. Many studies have demonstrated the importance of genetic and epigenetic molecular mechanisms in the maintenance of self-renewal and pluripotency. Stem cells are under unique molecular and cellular regulations different from somatic cells. Proper regulation should be ensured to maintain their unique self-renewal and undifferentiated characteristics. Understanding key mechanisms in stem cell biology will be important for the successful application of stem cells for regenerative therapeutic medicine. More importantly practical use of stem cells will require our knowledge on how to properly direct and differentiate stem cells into the necessary type of cells. Embryonic stem cells and adult stem cells have been used as study models to unveil molecular and cellular mechanisms in various signaling pathways. They are especially beneficial to developmental studies where in vivo molecular/cellular study models are not available. We have derived neural stem cells from human embryonic stem cells as a model to study the effect of teratogen in neural development. We have tested commercial neural differentiation system and successfully derived neural precursor cells exhibiting key molecular features of neural stem cells,which will be useful for experimental application. View Publication

Human pluripotent stem cells (hPSCs) have the potential for unlimited expansion and differentiation into cell types of all three germ layers. Cryopreservation is a key process for successful application of hPSCs. However,the current conventional method leads to poor recovery of hPSCs after thawing. Here,we demonstrate a highly efficient recovery method for hPSC cryopreservation by slow freezing and single-cell dissociation. After confirming hPSC survivability after freeze-thawing,we found that hPSCs that were freeze-thawed as colonies showed markedly decreased survival,whereas freeze-thawed single hPSCs retained the majority of their viability. These observations indicated that hPSCs should be cryopreserved as single cells. Freeze-thawed single hPSCs efficiently adhered and survived in the absence of a ROCK inhibitor by optimization of the seeding density. The high recovery rate enabled conventional colony passaging for subculture within 3 days post-thawing. The improved method was also adapted to a xeno-free culture system. Moreover,the cell recovery postcryopreservation was highly supported by coating culture surfaces with human laminin-521 that promotes adhesion of dissociated single hPSCs. This simplified but highly efficient cryopreservation method allows easy handling of cells and bulk storage of high-quality hPSCs. View Publication

Human embryonic stem cells (hESC) and induced pluripotent stem cells (hiPSC) assert a great future for the cardiovascular diseases,both to study them and to explore therapies. However,a comprehensive assessment of the viral vectors used to modify these cells is lacking. In this study,we aimed to compare the transduction efficiency of recombinant adeno-associated vectors (AAV),adenoviruses and lentiviral vectors in hESC,hiPSC,and the derived cardiomyocytes. In undifferentiated cells,adenoviral and lentiviral vectors were superior,whereas in differentiated cells AAV surpassed at least lentiviral vectors. We also tested four AAV serotypes,1,2,6,and 9,of which 2 and 6 were superior in their transduction efficiency. Interestingly,we observed that AAVs severely diminished the viability of undifferentiated cells,an effect mediated by induction of cell cycle arrest genes and apoptosis. Furthermore,we show that the transduction efficiency of the different viral vectors correlates with the abundance of their respective receptors. Finally,adenoviral delivery of the calcium-transporting ATPase SERCA2a to hESC and hiPSC-derived cardiomyocytes successfully resulted in faster calcium reuptake. In conclusion,adenoviral vectors prove to be efficient for both differentiated and undifferentiated lines,whereas lentiviral vectors are more applicable to undifferentiated cells and AAVs to differentiated cells. View Publication

Numerous publications have described the importance of bone morphogenetic protein (BMP) signaling in the specification of hematopoietic tissue in developing embryos. Here we investigate the full role of canonical BMP signaling in both adult and fetal liver hematopoiesis using conditional knockout strategies because conventional disruption of components of the BMP signaling pathway result in early death of the embryo. By targeting both Smad1 and Smad5,we have generated a double-knockout mouse with complete disruption of canonical BMP signaling. Interestingly,concurrent deletion of Smad1 and Smad5 results in death because of extrahematopoietic pathologic changes in the colon. However,Smad1/Smad5-deficient bone marrow cells can compete normally with wild-type cells and display unaffected self-renewal and differentiation capacity when transplanted into lethally irradiated recipients. Moreover,although BMP receptor expression is increased in fetal liver,fetal liver cells deficient in both Smad1 and Smad5 remain competent to long-term reconstitute lethally irradiated recipients in a multilineage manner. In conclusion,canonical BMP signaling is not required to maintain either adult or fetal liver hematopoiesis,despite its crucial role in the initial patterning of hematopoiesis in early embryonic development. View Publication

Selective and regulatable expansion of transduced cells could augment gene therapy for many disorders. The activation of modified growth factor receptors via synthetic chemical inducers of dimerization allows for the coordinated growth of transduced cells. This system can also provide information on specific receptor-mediated signaling without interference from other family members. Although several receptor subunits have been investigated in this context,little is known about the precise molecular events associated with dimerizer-initiated signaling. We have constructed and expressed an AP20187-regulated KDR chimeric receptor in human TF1 cells and analyzed activation of this gene switch using functional,biochemical,and microarray analyses. When deprived of natural ligands,GM-CSF,interleukin-3,or erythropoietin,AP20187 prevented apoptosis of transduced TF1 cells,induced dose-dependent proliferation,and supported long-term growth. In addition,AP20187 stimulation activated the signaling molecules associated with mitogen-activated protein kinase and phosphatidyl-inositol 3-kinase/Akt pathways. Microarray analysis determined that a number of transcripts involved in a variety of cellular processes were differentially expressed. Notably,mRNAs affiliated with heat stress,including Hsp70 and Hsp105,were up-regulated. Functional assays showed that Hsp70 and Hsp105 protected transduced TF1 cells from apoptosis and premature senescence,in part through regulation of Akt. These observations delineate specific roles for kinase insert domain-containing receptor,or KDR,signaling and suggest strategies to endow genetically modified cells with a survival advantage enabling the generation of adequate cell numbers for therapeutic outcomes. View Publication

The development of novel cell-based therapies requires understanding of distinct human hematopoietic stem and progenitor cell populations. We recently isolated reconstituting hematopoietic stem cells (HSCs) by lineage depletion and purification based on high aldehyde dehydrogenase activity (ALDH(hi)Lin- cells). Here,we further dissected the ALDH(hi)-Lin- population by selection for CD133,a surface molecule expressed on progenitors from hematopoietic,endothelial,and neural lineages. ALDH(hi)CD133+Lin- cells were primarily CD34+,but also included CD34-CD38-CD133+ cells,a phenotype previously associated with repopulating function. Both ALDH(hi)CD133-Lin- and ALDH(hi)CD133+Lin- cells demonstrated distinct clonogenic progenitor function in vitro,whereas only the ALDH(hi)CD133+Lin- population seeded the murine bone marrow 48 hours after transplantation. Significant human cell repopulation was observed only in NOD/SCID and NOD/SCID beta2M-null mice that received transplants of ALDH(hi)CD133+Lin- cells. Limiting dilution analysis demonstrated a 10-fold increase in the frequency of NOD/SCID repopulating cells compared with CD133+Lin- cells,suggesting that high ALDH activity further purified cells with repopulating function. Transplanted ALDH(hi)CD133+Lin- cells also maintained primitive hematopoietic phenotypes (CD34+CD38-) and demonstrated enhanced repopulating function in recipients of serial,secondary transplants. Cell selection based on ALDH activity and CD133 expression provides a novel purification of HSCs with long-term repopulating function and may be considered an alternative to CD34 cell selection for stem cell therapies. View Publication

OBJECTIVE: We used genetically engineered mouse hematopoietic progenitor cells (HPCs) to investigate the therapeutic effects of human apoAI on atherosclerosis in apoE(-/-) mice. METHODS AND RESULTS: Lentiviral constructs expressing either human apoAI (LV-apoAI) or green fluorescent protein (LV-GFP) cDNA under a macrophage specific promoter (CD68) were generated and used for ex vivo transduction of mouse HPCs and macrophages. The transduction efficiency was textgreater25% for HPCs and textgreater70% for macrophages. ApoAI was found in the macrophage culture media,mostly associated with the HDL fraction. Interestingly,a significant increase in mRNA and protein levels for ATP binding cassette A1 (ABCA1) and ABCG1 were found in apoAI-expressing macrophages after acLDL loading. Expression of apoAI significantly increased cholesterol efflux in wild-type and apoE(-/-) macrophages. HPCs transduced with LV-apoAI ex vivo and then transplanted into apoE(-/-) mice caused a 50% reduction in atherosclerotic lesion area compared to GFP controls,without influencing plasma HDL-C levels. CONCLUSIONS: Lentiviral transduction of apoAI into HPCs reduces atherosclerosis in apoE(-/-) mice. Expression of apoAI in macrophages improves cholesterol trafficking in wild-type apoE-producing macrophages and causes upregulation of ABCA1 and ABCG1. These novel observations set the stage for a cell therapy approach to atherosclerosis regression,exploiting the cooperation between apoE and apoAI to maximize cholesterol exit from the plaque. View Publication